On Mon, 2003-09-08 at 11:34, Peter Verveer wrote:

The documentation states that NA_ReturnOutput(numarray, shadow) should be used with the value returned by NA_OptionalOutputArray() for the shadow parameter.

The purpose of NA_OptionalOutputArray() and NA_ReturnOutput() is to support an optional output parameter and return value with a couple specific behaviors: 1. If no output array is specified to the function (it is left defaulted to None), then the function makes up an output array by cloning it (shape and type) from some 'master' array. The output array is returned as the result of the function. 2. If an output array is specified, then it may still need to be "shadowed" to correctly match the type, byteswap, and alignment requirements specified for the function. When a shadow output is created, it is used in all of the real calculations and then copied back onto the original array and deallocated at function exit. The function returns None.

Is it also possible to use a shadow array allocated otherwise, e.g. by NA_NewArray()?

I don't think so. It is however possible to return an array allocated by NA_NewArray() as-is.

Cheers, Peter

-- Dr. Peter J. Verveer Cell Biology and Cell Biophysics Programme EMBL Meyerhofstrasse 1 D-69117 Heidelberg Germany Tel. : +49 6221 387245 Fax : +49 6221 387242 Email: Peter.Verveer@embl-heidelberg.de

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